Zinc aluminate (ZnAl2O4) applied in the development of a propane gas sensor and in the design of a digital gas detector

When a propane gas sensor is developed based on a synthesized material, the goal is to use it in the development of new prototypes, which are applied in health and safety. In this work, zinc aluminate powders (ZnAl2O4) were synthesized using the colloidal method assisted with microwave radiation. The powders were characterized by X-ray diffraction, SEM, and TEM microscopy. With the diffraction analysis, the crystalline phase of the ZnAl2O4 oxide was demonstrated and with the electron microscopy images, the morphology of the particles was analyzed. In addition, based on these images, the particle size of the compound was estimated. With the calcined powders at 200 degrees C of ZnAl2O4, pellets were manufactured and electrically characterized (dynamic electrical tests) in atmospheres of dynamic propane at 200 degrees C, obtaining changes in electrical resistance as a function of time. The dynamic concentration of propane (1000 ppm) greatly influenced the excellent dynamic response in these operating conditions. Based on the electrical response of the sensor (ZnAl2O4), a first-order mathematical model was proposed and this was used to corroborate the stability of the sensor, its response to frequency and it was evaluated at 3s in order to estimate the resistance of the sensor R-p(t) when the sensor is exposed to propane gas. With the result obtained from resistance R-p(t)vertical bar(t=3), a prototype gas detector was designed based on the PIC16F887A microcontroller whose characteristics are: operating temperature of 200 degrees C, 1000 ppm operating concentration, 3s response time, 5 V supply voltage, 110 V alarm signal, optocoupler protection circuit, easy operation and easy repair. Our prototype has practical application in industries where high temperature safety systems are required, for example: boiler chimneys and heat exchangers.